1. Field of the Invention
The invention relates to a switching power converter, and more particularly to a control circuit of power factor correction (PFC) converters.
2. Description of the Related Art
The high current demand normally decreases the power efficiency in the power converter. The power loss of the power converter is exponentially proportional to its current.PLOSS=I2×R  (1)where I is the switching current of the power converter, R is the impedance of the switching devices such as the equivalent resistance of the inductor and the transistor, etc.
Therefore, parallel technologies are developed for reducing the power consumption of power converter. The PFC (power factor correction) power converter is utilized to improve the power factor of AC power source. The detail skill of the PFC circuit can be found in prior arts, such as U.S. Pat. No. 7,116,090 “Switching control circuit for discontinuous mode PFC converters”. The object of the present invention is to develop a control circuit for the parallel of PFC converters in order to improve the efficiency of the power supply. The number of parallel channels is no limit theoretically. Multi-phases technologies including synchronization and phase shift are designed to spread the switching noise and reduce the ripple.